The **M2UDS2-A2-R2** is a specific model identifier typically associated with **Industrial Control Relays** or **Monitoring Relays** (often manufactured by brands like Selec or similar industrial automation firms). Specifically, this part number refers to a **Digital Timer / Under-Over Voltage Monitoring Relay**. Below is a breakdown of its electronic specifications and characteristics. --- ### 1. Key Technical Specifications | Feature | Specification | | :--- | :--- | | **Device Type** | Voltage Protection / Monitoring Relay | | **Configuration** | 1 Phase - 2 Wire (1P2W) | | **Operating Voltage** | 85V to 270V AC/DC | | **Output Contacts** | 2 Changeover (SPDT) - 2 x 5A | | **Monitoring Range** | Under Voltage & Over Voltage Protection | | **Mounting** | DIN Rail Mount | | **Display** | Liquid Crystal Display (LCD) with Backlight | --- ### 2. Functional Electronic Components The device operates using several internal electronic sub-systems to ensure precise monitoring and switching: #### A. Power Supply & Sensing Unit * **Wide Range SMPS:** The "A2" designation usually implies a universal power supply capable of handling both AC and DC inputs (typically 85-270V). * **Voltage Divider Circuit:** Uses high-precision resistors to sample the incoming line voltage for the microcontroller to process. #### B. Microcontroller (MCU) * **Digital Logic:** Unlike older analog relays that use RC circuits for timing, this unit uses an MCU for digital accuracy. * **True RMS Sensing:** It calculates the True RMS value of the voltage waveform, ensuring accurate readings even if the power supply has harmonic distortion. #### C. Output Interfacing * **Electromagnetic Relays:** Contains two physical relays (indicated by the "R2" suffix). These act as the interface between the low-voltage logic and the high-voltage industrial load. * **Isolation:** The control circuit is optically or galvanically isolated from the power circuit to prevent damage during surges. --- ### 3. Protection Parameters The electronic logic allows the user to program the following thresholds: 1. **Under Voltage (UV):** Trips when the voltage falls below a set limit (e.g., protecting a motor from stalling). 2. **Over Voltage (OV):** Trips when the voltage exceeds a limit (e.g., protecting electronics from burnout). 3. **Hysteresis:** A small electronic "buffer" range to prevent the relay from chattering (rapidly switching on/off) when the voltage is hovering exactly at the trip point. 4. **Trip Time Delay:** A programmable delay (0-99 seconds) to ignore momentary voltage spikes or dips. --- ### 4. Wiring Diagram Concept ```text L (Line) ---------- [ (1) Aux Power (2) ] ---------- N (Neutral) | | Monitoring In ----- [ (L) Voltage Sense (N) ] | | Output 1 (R1) ------ [ (COM) (NO) (NC) ] Output 2 (R2) ------ [ (COM) (NO) (NC) ] ``` ---